Obesity is defined as the abnormal accumulation of body fat and is widely recognized as a significant contributing risk factor in many chronic diseases. It is well accepted that people who are obese are at significantly higher risk of heart disease, hypertension, diabetes, arthritis, and certain cancers, and consequently that obesity has direct impact on general health status and quality of life. Due to obesity's central role in determining general health and possible predisposition towards chronic diseases, there is a significant clinical and epidemiological need for the effective management of obesity.
In the management of obesity and diet, whether for the purpose of improved health, disease management or for lifestyle change, methods for the oversight of nutrition and exercise may be based upon the relationship between kilocalorie (kcal) intake and kilocalorie expenditure which yields a net energy balance (weight) for a period of time (Equation 1). If the energy balance is positive, this excess energy is typically stored within the body as a reserve source of energy, e.g. as fat, and therefore weight is gained.intake(kcal)−expenditure(kcal)=energy balance(kcal)  Equation 1.
By management of an individual's overall energy balance, desired weight loss/gain or maintenance of current weight may be achieved. To accomplish this objective, a variety of approaches have been attempted. These include the use of kcal energy expenditure calculators, and estimators of kcal intake. Intake monitoring, for instance, is typically accomplished through manually maintained diaries and/or external opinions based on estimate average kcals contained in that food group or images of the actual meal. These approaches are, in general, prone to compliance or estimation error.
Alternative approaches include the use of weight scales or body composition analyzers as indices of change in overall energy balance (weight), however they do not provide feedback regarding kcal energy expenditure as compared to kcal intake. In addition, these point in time or infrequent (periodic) devices rely on user compliance that may not accurately measure kcal energy balance. Furthermore, the absence of information about any other factors associated with weight gain/loss, e.g. kcal intake, significantly limits the utility of the information as a weight management therapy.
In short, the above approaches have proven insufficient to adequately provide the data and solutions necessary to resolve the terms of Equation 1 due to poor user compliance, inherent system inaccuracies due to periodic measurements, and/or imprecision in estimation of kcal intake. What is needed is a system that enables determination of kcal energy expenditure, energy balance and kcal intake, such that useful information regarding dietary habits and kcal energy expenditure may be used to drive personalized diet and exercise plans for an individual.